USDA Hardiness Zone 9b
Frost Dates for 94025 — Menlo Park, California
NOAA 1991–2020 normals from Palo Alto, CA (25 ft), 3 miles east.
Updated
In Menlo Park, the last spring frost (32°F) is around February 1 in half of years and has passed by March 4 in nine years out of ten. The first fall frost comes around December 7, as early as November 20 one year in ten, leaving a typical freeze-free season of 310 days (NOAA, Palo Alto, CA).
- Last spring frost
- February 1
- First fall frost
- December 7
- Growing season
- 310 days
- Hardiness zone
- 9b
50% probability
50% probability
freeze-free, 50%
25 to 30°F (-3.9 to -1.1°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 0%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
0 of 19 observed
NOAA normal
Frost risk by date in Menlo Park
Half of springs at Palo Alto, CA see their last 32°F night by February 1; only one in ten is past it by December 28, and one in ten still has one after March 4. Planting tender crops after February 14 leaves a 30% risk of a frost on them, after February 24 20%, and after March 4 10%. The 31 days between the even-odds date and the one-in-ten date is wider than at 53% of the 220 California stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by December 7 in half of years, as early as November 20 one year in ten, and holds off past January 6 one year in ten. A hard freeze of 28°F follows 15 days later, around December 22; in spring the one-in-ten date for 28°F is February 17, 15 days before the 32°F one. The freeze-free season lasts 310 days in a typical year, longer than at 68% of the 219 California stations; it reaches 347 days one year in ten and falls short of 272 one year in ten. On average 14 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 38 days longer, to about March 11, and return around November 21. A 24°F night is unusual: 13% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 5 | Feb 20 | Feb 27 | Mar 4 | Mar 11 | Mar 18 | Mar 28 | Apr 6 | Apr 15 |
| 32°F96% of yrs | Dec 28 | Jan 7 | Jan 16 | Jan 25 | Feb 1 | Feb 7 | Feb 14 | Feb 24 | Mar 4 |
| 28°F60% of yrs | Dec 15 | Dec 24 | Dec 28 | Dec 31 | Jan 4 | Jan 10 | Jan 21 | Feb 2 | Feb 17 |
| 24°F13% of yrs | too rare for a date | ||||||||
| 20°F1% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 3 | Nov 9 | Nov 13 | Nov 17 | Nov 21 | Nov 24 | Nov 29 | Dec 1 | Dec 8 |
| 32°F96% of yrs | Nov 20 | Nov 26 | Dec 1 | Dec 3 | Dec 7 | Dec 11 | Dec 16 | Dec 25 | Jan 6 |
| 28°F60% of yrs | Dec 3 | Dec 7 | Dec 11 | Dec 16 | Dec 22 | Dec 27 | Jan 1 | Jan 8 | Jan 25 |
| 24°F13% of yrs | too rare for a date | ||||||||
| 20°F1% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Palo Alto, CA, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 94025 →Compare Menlo Park with another place →
Weather by month in Menlo Park
July is the warmest month at Palo Alto, CA, averaging 79°F by day and 56°F at night; December is the coldest at 58°F and 39°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 42% of years and March still brings one in 10% of years.
Warmth for growing adds up to 3,364 growing degree days a year (base 50°F), fewer than at 75% of the 283 California stations. 39% of them (1,305) have built up by the end of June, and July adds the most, 544. Precipitation totals 15.2 inches a year, most in February (3.2") and least in July (0.0"); May to September bring 4% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 58 | 39 | 3.0 | 66% | 5 | 34 |
| Feb | 61 | 41 | 3.2 | 42% | 2 | 70 |
| Mar | 66 | 44 | 2.2 | 10% | <1 | 153 |
| Apr | 70 | 45 | 1.0 | 2% | <1 | 226 |
| May | 73 | 50 | 0.4 | 0% | 0 | 354 |
| Jun | 79 | 53 | 0.1 | 0% | 0 | 468 |
| Jul | 79 | 56 | 0.0 | 0% | 0 | 544 |
| Aug | 79 | 55 | 0.0 | 0% | 0 | 527 |
| Sep | 80 | 53 | 0.1 | 0% | 0 | 489 |
| Oct | 74 | 48 | 0.6 | 0% | 0 | 348 |
| Nov | 64 | 43 | 1.6 | 27% | 1 | 117 |
| Dec | 58 | 39 | 3.0 | 75% | 6 | 35 |
Monthly normals 1991–2020 at Palo Alto, CA (25 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Redwood City, CA, 3 miles northwest of Menlo Park, has a last frost 15 days earlier (January 17), a first frost 5 days later (December 12), a season 23 days longer.
When it snows in Menlo Park, California
Measurable snow is rare here: only 0 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Palo Alto, CA, 2.5 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 94025
| When | What to do |
|---|---|
| November 23 – December 7 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 7 – December 21 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 4 – January 18 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 1 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 14 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 23 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 7 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 94025 is 3 miles from Palo Alto, CA, which stands at 25 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 94303 (Palo Alto). The 2023 USDA Plant Hardiness Zone Map lists ZIP 94025 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across California →
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.